NO339748B1 - Double packing box air inversion and steam curing with onsite facilities - Google Patents

Abstract

Installation of a flexible cured in place liner by inverting the liner with air and curing the liner with steam introduced through a perforated lay flat hose without deflating the liner between the inversion and cure. The installation is performed with an apparatus having two independently operable glands with at least one fluid inlet port installed on the line downstream of the second gland liner. As the liner reaches the distal end of the conduit to be lined, it enters a sample and porting pipe with an exhaust pipe gland and exhaust pipe and it is pierced by a rigid porting tool. Steam is then introduced into the lay flat hose to cure the resin and is exhausted through an exhaust hose connected to a controllable exhaust pipe. After curing steam is replaced with air to cool the liner, the ends are cut to restore service through the host pipe.

Description

The invention relates to inversion and installation of cured liner on site by air inversion and steam curing and an apparatus with double guide seals for inversion and curing of the liner. The method and apparatus provide a restraint strap to regulate the rate of inversion and a perforated horizontal flat hose for introducing steam for curing with an outlet port for continuous flow without emptying the liner prior to steam curing. The method and apparatus are particularly suitable for installation in liners from about 18 to 36 inches to about 72 inches and more.

It is generally known that conduit pipes or pipelines, in particular underground pipes, such as drain pipes, water pipes and gas pipes used to carry fluids, often require repair due to fluid leakage or weakening. The leakage can occur inwards from the environment or the leading part of the pipeline. Alternatively, the leakage can occur outwards from the conducting part of the pipeline to the surroundings. In all cases, it is desirable to avoid such leakage.

The leak may be due to incorrect installation of the original pipe or weakening of the pipe itself due to normal aging or the effects of either transporting corrosive or abrasive material. Cracks at or near pipe joints may be due to environmental conditions, such as earthquakes or the movement of large vehicles on the overlying surface or similar natural or man-made vibrations or other such causes. Regardless of the cause, such leakage is undesirable and can lead to waste of fluid transported in the pipeline or lead to damage to the environment and possibly damage to public health. If the leak continues, it can lead to structural failure of the existing conduit due to loss of ground and lateral support of the conduit.

Due to ever-increasing labor costs, energy costs and machine costs, it is becoming increasingly difficult and less economical to repair underground pipes or parts that may leak by digging them up and replacing the pipes. As a result, various methods of on-site repair or rehabilitation of existing pipelines have been developed. These new methods avoid the expense and risk associated with digging up and replacing pipes or pipe sections and the inconvenience to the public. One of the most successful pipeline repair or trenchless rehabilitation processes currently in widespread use is called the Insituform® process. This method is described in US patent nos. 4,009,063, 4,064,211 and 4,135,958.

In the standard implementation of the Insituform process, an elongated, flexible tubular liner of felt cloth, foam or similar resin-impregnatable material with an outer, impermeable coating that has been impregnated with thermosetting resin is installed in the existing pipeline. In general, the liner is installed using an offset process as described in the last of the two identified Insituform patents. In the warping process, a radial pressure pushes against the interior of a warped liner, against and into engagement with the inner surface of the pipeline. However, the Insituform process is also practiced by pulling a resin-impregnated liner to the conduit using a rope or cable and using a separate fluid impermeable inflatable bladder or liner that is twisted into the liner so that it can harden against the inner wall of the existing pipeline. Such a resin-impregnated liner is called "hardened pipes" or "ClPP liners" and the installation is called a ClPP installation.

Flexible pipe liners of the CIPP type have an outer, smooth layer of a relatively flexible, substantially impermeable polymer that coats the outside of the liner in its initial state. When inverted, the impermeable layer will be on the inside of the liner after it has been inverted during installation. As the flexible liner is installed into place in a pipeline, the pipeline is pressurized from within, preferably using a shearing fluid such as water or air to force the liner radially outward to grip and conform to the inner surface of the existing pipeline .

Typically, an overturning tower is set up at the installation site to provide the necessary pressure to overturn the casing or a bladder. A displacement unit is also shown and described in US Patent Nos. 5,154,936, 5,167,901 (RE 35,444) and 5,597,353. Curing can be initiated by introducing hot water into the twisted liner through a recirculation hose attached to the end of the twisted liner. Inversion water is recirculated through the heat source, eg a hot water tank or a heat exchanger and returned to the inverted liner until its curing is complete. The resin that is impregnated into the impregnable material is then cured into a hard, tight fitting and rigid pipe liner in the existing pipeline. The new liner effectively seals any cracks and repairs any pipe section or pipe joint weakening to prevent further leakage either into or out of the existing pipeline. The cured resin also serves to strengthen the existing pipeline wall to provide additional structural support for the surrounding environment.

The tilting tower, which was time-consuming to construct, required the worker to be 10 meters above the ground and often close to trees or power lines. The process was improved with a device that allowed Insituform to generate a hydraulic pressure using a choke valve. The liner was brought to the top of the apparatus and pulled through the valve by pressurizing water under the valve. The pressurized water applied a force to the nose of the liner so that it was inverted to the pipe being rehabilitated. These devices for the rehabilitation of smaller pipes have been in use for about 15 years.

The main disadvantage of using these appliances with water is the quantity and availability of inverting water. The water is typically heated from 55°F to 180°F to effect the cure and then cooled by adding more water to 100°F before being released into an acceptable disposal system.

This drawback can be solved by using air instead of water to produce the inverting power. After the liner is completely impregnated, it can be cured with steam. Although water is required to produce the steam, the amount of water in the form of steam is only about 5 - 10% of that required for water inversion, curing and cooling. This means that steam can be used for curing even if water is not readily available on site. The drastic reduction in the amount of water is the result of the higher energy available from a pound of water in the form of steam as opposed to a pound of heated water. A pound of steam condensed to a pound of water emits about 1000 BTUs while a pound of water emits only one BTU for each degree drop in temperature. This reduced water requirement plus a virtual elimination of the heating cycle greatly reduces cure cycle and installation time.

With this obvious advantage of using air inversion and steam curing, one wonders why the industry has been so slow to abandon water inversion and hot water curing.

When water is used to invert the resin-impregnated liner, the non-inverted portion of the liner is pushed up from the invert nose of the inverting apparatus by a force equal to the amount of water displaced by the liner. In the case of CIPP liners, this means that the effective weight of the liner is significantly reduced, as well as the force required to pull the non-inverted liner forward to the invert nose. When air is used to produce the inverting force, the non-inverted liner rests on the bottom of the pipe and the air pressure acting on the inverting nose of the liner must pull the full weight of the liner forward.

Three forces must be overcome to invert a ClPP liner, regardless of what is used to generate the inverting energy. These forces are:

1. Force required to invert the liner (turn the liner inside out). This force varies with casing thickness, material type and the ratio of casing thickness to diameter 2. The force required to pull the casing from the inverting device to the inverting nose. 3. The force required to pull the liner through the inverting apparatus.

Force number one (1) above is generally the same for both air and water inversions.

Force number two (2) varies greatly between air and water and can limit air inversions. There are limits to how much pressure can be applied to invert a liner without adversely affecting the quality of the installed ClPP liner and/or damage to the existing conduit. Lubricant can be used for both water-air inversion to reduce the required pulling force.

Force number three (3) may vary based on the device design. In most apparatus currently in use, the force required to pull the liner through the apparatus will increase as one or both forces one and two increase. This is because in order to increase the available inversion energy, a typical apparatus in use today limits the loss of pressurized fluid from the pressure chamber below the casing entry point to the apparatus and the end of the pipe being inverted. This limitation is typically achieved by increasing the air pressure in a pneumatic throttle packing box or using a packing that is energized by the inverting fluid. The inward movement is typically limited by the packing material and the compression of the inverted ClPP liner. This in turn produces an increase in the friction between the inverted ClPP liner and the gasket.

Considering these obvious advantages of steam curing compared to hot water curing, the use of steam has been suggested also considering the energy it carries. Air inverting a bladder and flowing steam for curing has been described in Insituform US Patent Nos. 6,708,728 and 6,679,293. The methods described in these patents utilize indentation and inflation technology and are currently used in smaller liners. They are advantageous in relation to water displacement with a smaller diameter. However, the described method does not employ the use of a horizontal, flat tube to introduce steam. Furthermore, the use of a punctured container as described in these patents is not well suited for liners with medium and larger diameters. In general, medium-sized liners are considered to be between 18 and 36 inches in diameter. Larger diameters are those with a diameter of 42 inches and more.

Accordingly, it is desirable to provide a method for improved air inversion/steam curing installation of ClPP liners that utilizes a containment strap and horizontal flat tubing for distribution of steam to the inverted liner to ensure complete curing without thermal stratification and without having to evacuate the liner prior to injection of steam for curing.

US 5358359 describes an apparatus for driving a flexible liner into an existing pipeline. The device comprises a flexible, tubular curtain means

connected to an inversion chamber. Two inflatable tubular bladders of cushions are used to press against the curtain material and seal the curtain material and the warp lining that slides through it. The inverting liner is fitted to the outlet end of the inverting chamber in which the inverting pressure is developed.

In general, a liner for a pipe that is cured in place is inverted according to the invention as defined in the claims using an installation apparatus with two selectively rigid gaskets. The device makes it possible to introduce a curing fluid after turning without emptying the liner. An open frame is used to secure the liner being inverted before being passed between a first selectively rigid packing box to form an air or vapor seal and a second selectively rigid packing box to form an air seal for inversion.

In a preferred embodiment of the invention, the inversion apparatus is a vertically placed frame for placement over an entry hole, so that a resin-impregnated liner attached to the frame is inverted and passed through first and second stuffing boxes before it reaches the existing conduit. The liner has a dry part which is attached to and which is passed through the frame provided with at least one inversion curing fluid port located between the two stuffing boxes. Each packing box has two fixed elements. In one embodiment of the invention, an element is a fixed element on one side and which acts with an opposite offsetable fixed element to form the packing box. Alternatively, both fixed elements can be displaced to form seals. The first or upstream packing may comprise a compressible material which is secured over the solid elements to ensure formation of the vapor seal during the curing cycle. Preferably, the fixed elements are tubes, where the inverted part of the lining provides a substantial compressive material to form a suitable vapor seal. The second or air seal is placed at a specific gap during the first half of the inversion, depending on the thickness of the lining. An increase in the inversion pressure will not require additional pressure against the resin-impregnated lining.

The part of the liner attached to the entry frame that is passed through the first and second gaskets is kept dry and is not impregnated with resin. At least one fluid port for introducing inversion and then curing fluid is formed through the wall of the dry portion of the liner. In a preferred embodiment of the invention, a first port is between the two seals for the introduction of inversion fluid, for example air and also for the introduction of steam during the curing phase. A second port is installed in the wall of the dry part of the liner downstream of the second packing for introducing the inversion fluid, such as air, to invert the liner.

In an embodiment of the invention, the inventive improvement's sleeve of impregnable material can be placed in the dry inlet part of the lining, so that the inverted lining with an impermeable layer on the outer surface can easily be passed through the dry part of the lining which is fixed in the frame. The sleeve facing the impregnable layer of the invert liner can be lubricated to improve inversion through the stuffing box.

A selective opening and elevation of the stuffing boxes allows for the passage of a restraint cable or strap to regulate the speed during the second half of the inversion and the passage of a horizontal flat hose and steam attachment for the introduction of hot air or steam during curing. The use of a perforated, horizontal and flat tube for steam curing allows steam to be introduced along the entire length of the inverted liner to avoid the consequences of the accumulation of condensation which often leads to poorly cured parts of the liner during steam curing. The double packing boxes make it possible to pass the horizontal, flat steam hose with steam attachment through the frame and into the inverted liner without emptying it before introducing curing fluid. Preferably, the horizontal, flat tube has alternating holes arranged along its length near the edge. Typically, this is Va to 1 Vz inches from the edge of the lying flat hose. This hole pattern ensures distribution of steam in the bottom along the entire length of the liner regardless of the direction of the hose.

A sample and porting sleeve with at least one pre-installed partition suitable to form an outlet port at the distal end of the inverted liner to receive a porting tool can be placed in the distal access point. After the inversion is stopped with the distal end of the liner captured by the porting sleeve, a porting or slotted drill can be used to form an outlet port in the inflated liner. An adjustable outlet hose is connected to the outlet port and steam is introduced into the liner through the horizontal flat hose and the curing resin without emptying the inverted liner.

Accordingly, an object of the invention is to provide an improved method of inverting a ClPP liner.

It is a further object of the invention to provide a double packing box apparatus for inverting a ClPP liner with air and curing with steam.

It is further an object of the invention to provide an improved method for air inversion and steam curing of a ClPP liner with an apparatus with rigid, double packing boxes.

It is further an object of the invention to provide an improved method where a pipe lining is cured in place and inverted with air and cured with steam without the lining being emptied after being placed in an existing conduit pipe.

It is a further object of the invention to provide a method and an apparatus which is suitable for air inversion and steam curing, where the liner is inverted through a segment of the liner which is shaped with at least one port for the introduction of air and/or steam.

It is further an object of the invention to provide an improved method for air inversion of a ClPP liner with a restraint strap and horizontal, flat tube for introducing steam to cure the liner.

Other advantages and purposes of the invention will appear from the specification.

The invention shall be described in more detail in the following, where:

Figure 1 is a schematic perspective view of an apparatus with double, rigid stuffing boxes for air inversion and steam curing of a pipe lining cured in place and which is constructed and arranged according to the invention,

Figure 2 is a schematic view of the right side of the inversion apparatus in Figure 1,

Figure 3 is a perspective view of the inversion apparatus of Figures 1 and 2 with an installed ClPP liner and air and steam connections during steam curing in accordance with the invention, Figure 4 is a schematic sectional view showing the position of the gaskets of the apparatus of Figure 3 below the first half of the air inversion, Figure 5 is a schematic sectional view showing the position of the packing of the apparatus of Figure 3 halfway through the inversion, Figure 6 is a schematic sectional view showing the position of the packing box of the apparatus of Figure 3 during the second half of the inversion, Figure 7 is a schematic sectional view showing the position of the gasket of the apparatus of Figure 3 at the completion of the inversion, Figure 8 is a schematic sectional view showing the preparatory steps for connecting the horizontal flat hose to the steam inlet prior to curing , Figures 9(a) and 9(b) are schematic plan views and sections of a flexible porting sleeve with an installed partition attached for use with the inverted liner , Figure 10 is a sectional view of a partition mount of Figure 9 showing details of the construction of the porting of an inverted end of a fully inverted liner which is captured by the sleeve; Figure 1 l(a)-l l(g) is a schematic cross-sectional view of the method of forming an outlet port in the inverted liner captured in the porting sleeve of Figure 9 and an inverted hardened liner in place which is taken to a sample and porting pipe before and after porting with a porting tool, Figures 12(a) and 12(b) are schematic cross-sectional views of the steps for installing a condensate drain at the distal end of the inverted liner after performing the steps shown in Figure 11 (a)-ll(g). Figure 13 is a schematic sectional view showing the position of the gaskets of the apparatus of Figure 3 with air/steam supply hose attached in preparation for introducing steam for curing; and Figures 14(a) and 14(b) show an outlet porting technique suitable for smaller diameter casing.

An improved method and apparatus for air inversion and steam curing of a ClPP liner in accordance with AS TM F1216 Standard Practice for Rehabilitation of Existing Pipelines and Conduits by the Inversion and Curing of a Resin-Impregnated Tube is described. The method and apparatus are well suited for installation of medium diameter CIPP casing working from the surface through the structure, eg entry holes to rehabilitate existing buried pipelines and conduits.

An inverting device 11 is constructed and arranged according to the invention shown in figure 1. The device 11 is a rigid frame dimensioned for placement over the inverting access to the conduit to be lined. The apparatus 11 is fabricated from metal rods or tubes to form a frame 12 of a sufficient width "w" to receive a flat tube liner for curing in place, for installation. The frame 12 is substantially rectangular in the embodiment shown and has a rectangular entrance opening 13 with several hooks 14 for attaching the inverting liner. The opening 13 has a thickness "t" which is chosen so that the dry part of the inverted moistened liner can be attached to hooks 14 and inverted through the entrance opening 13.

The frame 12 has a height "h" sufficient to support a first or upstream packing 16 formed by a fixed packing member 17 and an opposing co-operating movable packing member 18 located near the inlet 13. A pair of air cylinders 19 are attached to the end of the frame 12 and connected to the movable element 18 so that this can move towards the fixed element 17.1 the embodiment shown, the cylinders 19 are pneumatic air cylinders with linear guide bearings 20a. The cylinders 19 can be any mechanical closing mechanism or motor of any type, for example a hydraulic or electrical or mechanical clamping mechanism.

A second or downstream packing 21, shaped in the same way as the first packing 16, has a rigid packing member 22 attached to the frame 12 and a movable packing member 23 on a pair of linear guide bearings 20b with an attached air cylinder 24. The height "h" of the frame 12 is chosen to provide sufficient space between the first packing 16 and the second packing 21 to enable the use of a fluid inlet port installed in the dry part of an inverted liner for the introduction of air and/or steam. An inverting fluid inlet opening is installed in the dry part of the inverted liner and placed downstream of the second packing 21 and before the entry opening. A full description of the liner and installation ports will be provided below.

In the embodiment shown in Figure 1, the frame 12 has a bottom 25 formed by two side tubes 26 and 27 welded to a rectangular front frame 28 formed by a bottom tube 29, two vertical side tubes 31 and 32 and an upper tube 33. Vertical tubes 33 and 32 are welded to the bottom side tubes 26 and 27 respectively. A corresponding, rectangular back frame 34 formed by a bottom tube 36, two side tubes 37 and 38 and an upper tube 39, is welded to the bottom side beams 26 and 27 in the same way as the front frame 28. A pair of first horizontal gasket support tubes 41 and 42 are fixed between the front side tubes 31 and 32 of the front frame 28 and the side tubes 37 and 38 of the rear frame 34. Likewise, a pair of support beams 43 and 44 are fixed between the front frame 28 and the back frame 34 to support the second gasket 21. Four inclined support tubes 46, 47, 48 and 49 are welded between the front and back of the side tubes 26 and 27 to provide stability to the frame 12. Although inclined support tubes are shown, it is contemplated that rectangular support members forming a step may also be used to provide a working platform at or around the height of the second packing 21.

Air cylinders 19 are shown mounted above the first gasket 16 and the second gasket 21. Each cylinder is connected to a coupling, so that it can run on a pair of linear guide bearings 20. Air cylinders 19 each have an air coupling 50 connected to an air switch control board

53 shown in Figure 3.

The fixed packing element 17 and the movable packing element 18 of the first packing 16 have a compressible, high temperature resistance blankets 54 and 56 mounted on the opposite surfaces. This compressible material 54 and 56 will conform to and tightly grip an inverted liner with a restraint strap and lying flat tubing as they are passed through a first gasket 16 during the second half of the inversion. In addition, the compressible material 54 and 56 form a suitable seal when the first seal is closed during steam curing.

The rigid, cooperating opposing surfaces of the elements 22 and 23 of the second gasket 21 can be flat. The curvature can be added to the mating surfaces by welding a small diameter tube to the beams 22 and 23 or by using a former for members 22 and 23. This curved surface provides a smoother surface for gripping the inverted liner.

The second seal 21 forms the air seal during the air inversion. At the beginning and first half of the inversion, the second packing 21 is closed to a distance of about four times the thickness of the casing using a gap setting device. This device can be suitably adapted spacers placed on the guide bearings 20a and 20b. After the restraint strap and the lying flat tubing are passed through the second gasket during the second half of the inversion, the space of the second gasket 21 is reduced to approximately twice the liner wall thickness.

Using this design, an increase in the inverting air pressure will cause the casing to invert without increasing the pressure against the casing at the second packing 21 by means of elements 22 and 23. The air pressure to the cylinders 19 can be increased to prevent the packing 21 from opening to a gap which is more than twice the casing thickness. The gap adjustment device, e.g. spacers placed on the guide bearings or threaded bolts, prevents a reduction of the gap beyond what is desired.

The seal around the inverted liner is produced by the dry part of the liner itself, so that the seal has an identical profile and dimension. Thus, there is no need to worry about forming a seal at the edges of the flattened liner. The length of the edge perimeter of the flattened lining is minimal compared to the long side of the finished lining, so that loads on the edges are minimal and no additional seaming or supporting of the edges is needed. This allows straight, rigid pipes or beams to be used to form the seal. The method and apparatus as described provides an advantage over prior inversion devices. In these latter devices, forming a seal at the edges becomes difficult because of the inversion that continues downstream of the seal or gasket. Here it is an advantage that the inversion of the casing has begun before the casing passes through a gasket to form an inversion and hardened seal.

Figure 3 shows an apparatus 11 with an inverted liner 101 attached hooks 14 on the entrance opening 13 during the steam curing stage. The liner 101 is produced with a dry end part 102 and is moistened just before where the inverting liner is led to the conduit for rehabilitation. An air inlet port 106 is arranged in a dry area 102b between a second seal 21 and the beginning of the humidification at area 103. An air hose 107 is connected to the air inlet port 106 and an air source (not shown).

An air/steam inlet port 108 is also installed in the lining area 102a between the first gasket 16 and the second gasket 21. A steam pipe 109 is connected to the steam inlet port 108 and to a heater (not shown).

The apparatus 11 in Figure 3 shows an installation and placement of a first gasket 16 and a second gasket 21 after the inversion has been completed and during steam curing. Here, the first packing 16 is closed to form a steam seal over the steam which is fed to the steam inlet port 108. The second packing 21 is open, so that steam can be fed into the inverted liner 101 through the horizontal, flat hose installed at the liner 101 to effect the curing.

The sequence of the inversion and curing steps is shown schematically in sequence in Figures 4 - 13. During the first half of the inversion in Figure 4, the first seal 16 is open and the second seal 21 is closed to a gap of 4T (four times the thickness of the liner 101) using spacer adjusting devices. Inversion air is fed into an air inlet port 106 from an air inlet hose 107 to allow the liner 101 to invert within a dry liner portion 102b and to the conduit being lined. Halfway through the inversion, the first gasket 16 is closed to engage a restraint strap 111 and a lying flat tube 112 as shown in Figure 5. The lying flat tube 112 has a closed end 112a. During the second half of the inversion, as shown in Figure 6, the second seal 21 is opened and inversion air is fed into the air inversion inlet port 106 to complete the inversion. At this point, the second seal 21 is closed and the first seal 16 is opened as shown in figure 7.

At this point, and when the first packing 16 is opened, the horizontal flat tube 112 is cut across the first packing 16 and a steam knee is attached to the cut end. The steam elbow 113 and excess flat hose 112 are sunk into the frame 12 between the first gasket 16 and the closed second gasket 21 and the elbow 113 is attached to the rear of the air/steam port 108. Alternatively, a flexible flat adapter can be attached to the flat tubing on the outside of the inverted area which can then be inserted into the air/steam port to facilitate the addition of steam to the inverted tube. The flat-lying adapter can be a thin, tubular and rigid and flexible metal sleeve with an extended profile that prevents it from being drawn into the air/steam port. The tube part of the sleeve is inserted into the cut end of the horizontal flat hose and inserted into the inlet port. The horizontal, flat tubing is then gripped between the expanded area of the sleeve and the port. The slack in the horizontal flat tube 112 will fall into the inverted end when the first seal 16 is closed and the second seal 21 is opened at the beginning of the steam cycle as shown in Figure 13.

In one embodiment of the invention, an inversion-enhancing sleeve 115 of an impregnable material can be placed in the dry inlet portion of the liner to facilitate inversion through the packing. In this case, an invert liner with an impermeable layer on the outer surface will easily be passed through the dry part of the liner attached to the frame. The sleeve facing the impermeable layer of the inverted liner can be lubricated to facilitate inversion through the gasket.

Just after the completion of the inversion, the inverted liner 101 is ported into the downstream access port. A flow port 130 in the inverted distal end of the liner 101 as shown in Figure 10, arranged without the liner 101 being emptied. A flexible porting sleeve 117 as shown in Figures 9(a) and 9(b) is fixed in the receiving entry hole. The sleeve 117, which can be fixed with smaller diameters, comprises an outlet partition wall attachment 118 and a condensate drainage partition wall attachment 119. Figure 9 shows an attachment 110 in section attached to the sleeve 117 by a flange 121 and bolts 122. The sleeve 117 is attached at the receiving end of the existing conduit and liner 101 is inverted through the sleeve and held therein. At the same time, an outlet port 130 and a condensate port 163 are formed at the partition mount 118 and 119 with a mounting sleeve 139 installed in the porting sleeve 117 to use the method as outlined in connection with Figures 11 and 12.

The outlet port 130 is formed at the distal end following the steps shown in Figure 1 l(a)-l l(g). The port sleeve 117 may be formed from a length of the ClPP lining material provided with a second partition wall attachment 119 to form the second port 163 for a condensate drain 164 as shown in Figures 14(a) and 14(b).

A cap 138 is removed and a ball valve 171 is installed on the attachment sleeve 139. The ball valve 171 is closed with a nipple 172 which is installed thereon. A hole saw 173 with a drill rod 174 is inserted into the nipple 172 and a threaded hole saw rod guide 176 is attached to the end of the nipple 172. A drill 173 is attached to the rod 174. The ball valve 171 is opened on port 130 or 163 and the drill 177 is started to cut a hole 130 and 163 while maintaining the air pressure in the liner 101. When the port 130 and 163 are completely cut off, the ball valve 171 is closed and the drill 177 and the hole saw 173 are removed from the attachment 131. The outlet hose 61 is then attached to the nipple 172.

The condensate port 163 can be formed according to the same steps as shown in figure 1l(a) to 1l(g). After removing the drill 177, a condensate pipe gasket 181 is placed on the nipple 172 and a condensate drain hose 182 is placed in the gasket 182 to reach the bottom of the liner 101. The gasket 181 is tightened to prevent the hose 182 from moving. For smaller diameter liners, outlet and condensate ports can be provided using a porting tool as shown in Figures 14(a) and 14(b).

In figure 13, steam is introduced to the fixed, perforated and lying, flat hose 86 to initiate curing of the resin in the inverted liner 101 with the seals 16 and 21 in the position shown in figure 3.1 an example of embodiment of the invention, it is lying, flat hose 86 a high-temperature, thermoplastic pipe with 4-inch diameter and one-eighth-inch openings. The size and distance may vary depending on the heat source and the liner's size and length. The openings are made at one-foot intervals of one-half inch from the folded edges at opposite edges. The distance from each edge may vary depending on size and length.

The opening pattern described provides more steam at the proximal end of the liner 101 and ensures good mixing even if the hose 112 is twisted. This also ensures that the steam is injected into a condensate which forms in the tube which is inverted to cure the part of the resin in the liner covered by the condensate build-up. Steam is supplied from the steam inlet hose which is regulated by a valve manifold. The steam flow is adjusted to maintain a cure pressure of approximately 3 - 6 psi until the cure cycle is completed.

In a typical installation, openings in the horizontal flat tubing 112 are formed approximately one foot apart when a four inch tubing is folded and cut in an alternating pattern approximately one half inch in from the top and bottom of the folded tubing. Thus, two holes are formed at each location, so that the two holes are formed in an alternating pattern. The lying flat tube 86 has a closed distal end and can vary in size from about 2 to 8 inches in diameter. The diameter of the openings ranges from about 1/8 to 1/2 inch and preferably between about 3/16 to 3/8 inch in diameter. Depending on the particular resin chosen, one with a high exotherm during the cure will only require smaller sized openings as less steam is required to complete the cure. In some systems, more than one perforated, horizontal flat hose can be used.

At the same time as the outlet port 130 is installed, a steam elbow or flexible flat adapter 113 is attached to the proximal end of the horizontal flat hose 112 above the inlet opening 13. The elbow 113 and excess horizontal flat hose 112 are lowered through the first gasket 16 and attached to the closed air/steam port 108. As shown in Figure 13, the first gasket 16 is then closed and the air/steam supply hose 109 is connected to the steam inlet port 108 on the liner 101 and the second gasket 21 is opened. At this point, air and steam are introduced into the air/steam inlet port 108 and passed through the perforated, horizontal, flat tubing to initiate heating of the liner 101. After a 3°F rise in temperature is detected at the distal end, full steam added to effect the curing. The outlet steam passes through an outlet hose connected to the outlet port 130 at the distal end of the liner 101.

The installation procedure is as follows.

1. A moistened ClPP liner with a first dry end is turned inside out and passed through the entrance opening and attached to hooks. The liner is placed through both gaskets in the entry hole of the conduit pipe. An air hose is attached to the inlet opening on the dry part of the liner. 2. A 2" supply hose is connected from the outlet end of the air/steam manifold to the air inlet of the inversion unit. Air pressure and temperature gauges (lea) are connected to an air/steam manifold. 3. A restraint rope and a perforated horizontal flat hose are connected to another end of the ClPP liner 4. A suitable lubricant is applied to the absorbent felt layers at the inlet of the improvement sleeve located in the dry part of the liner.

The installation sequence as described in connection with figures 4 - 8 is then followed.

As shown in Figures 14(a) and 14(b), there is a PVC or rigid pipe sample casting of metal with an outlet pipe assembly 161 with a casting 162 and steel pipe 163 in the far downcomer hole adapted to receive an inversion pipe. As the nose of the inversion reaches the far entry hole, the inversion is lowered to allow the casing to reach the sample casting 162 and the steel tube 163. The inversion is stopped when the nose of the inversion casing is approximately one diameter past the end of the sample casting 162.

The restraining rope is released and the inverted liner is ported by inserting a steel porting tube 164 with a penetration tip 166 at the lower end and valve 167 at the upper end. A flange or o-ring 168 provides a tip on the porting tube 164 to prevent the tube 164 from penetrating the other side of the liner.

An operator responsible for porting notifies the inverter that he is prepared to port the inverted liner so that the air supply can be adjusted to maintain pressure over the inverted liner after it has been ported.

After the casing has been satisfactorily ported, the porting pipe valve 167 is closed and an outlet hose with a valve at the far end is attached to the porting pipe valve 167. The control of the outlet is now carried out at the far end of the outlet hose.

Upon completion of the inversion, control of the outlet is now done at the far end of the outlet hose. The outlet valve and air inlet regulator are adjusted as needed to maintain good flow and recommended heating and curing pressure. Outlet and condensate ports are installed as shown in Figure 1 l(a) to 1 l(h).

The boiler outlet is closed and the steam supply hose is attached to the air steam manifold. Heating is now started. The inner surface temperature at the 6 o'clock position, in the far entry hole, is monitored. The heated steam-air mixture should be approximately 180°F and continue until there is a 3°F rise at the far entry hole interface. After heating is complete, the amount of air in the air/steam mixture is slowly reduced to zero and full steam flow is maintained at 225 to 240°F at the recommended curing pressure. Full steam curing continues for between 1 to 4 hours as required, depending on liner length and thickness as well as the surrounding environment.

After the curing cycle is complete, steam is slowly shut off and air is simultaneously added to maintain the recommended curing pressure. The liner is then cooled for at least 15 minutes or until the interface temperature is 130°C at the far end, i.e. at the longer of the two.

Steam supply is then shut off at the boiler. When the boiler supply hose pressure reaches zero, the steam supply hose is disconnected. When the cooldown is complete, the air compressor is shut down and the pressure in the air hose is released and the air supply hose is disconnected.

At this point, the ends are removed from the lined pipe and the services are reinstalled using standard procedures.

The flexible lining which is cured on site is of a known type. It is formed from at least one layer of flexible resin impermeable material, for example a felt layer with an outer impermeable polymer film layer. The felt layer and the film layer are stitched together along a line to form a pipe liner. A compatible thermoplastic film in the form of a tape or extruded material is placed on or extruded over the seam line to ensure liner impermeability.

For linings with larger diameters, several layers of felt can be used. The felt layers can be made of natural or synthetically flexible resin-absorbable materials, for example polyester or acrylic fibres. The outermost impermeable film may be a suitable polyolefin, for example polypropylene or another quality polymer which can withstand steam temperature, as known in the art. In the initial step, in all trenchless rehabilitation installations, the existing pipeline is prepared by cleaning and video inspection.

Before installation begins according to the method of the invention, a thermosetting resin is impregnated into the felt in a lining by a process called "wetting". The dewetting generally involves injecting resin into the felt layer through the end or an opening arranged in the impermeable film layer and sucking out a vacuum and passing the impregnated liner through nip rollers as known in the art. Such a method for vacuum impregnation is described in Insituform US patent no. 4,366,012. A wide range of resins can be used, for example polyester, vinyl esters, epoxy resins and the like which can be modified as required. It is also desirable to use a resin which is relatively stable at room temperature, but which hardens easily when heated.

The air inversion and steam cure installation of cured-in-place pipe (CIPP) liners, as described herein, is a cost-effective and efficient method for installing and curing medium to large diameter (18" - 84") liners. Using steam to cure without draining the liner requires procedures that differ greatly from the more typical hot water cures of ClPP liners of the same diameter. The use of steam curing for medium and large diameter CIPP liners also requires a different technology to that used for steam curing smaller diameter ClPP liners (6" - 15").

Used correctly, steam is a more environmentally friendly curing method than water in that it uses only about 5% of water and between about 15 to 30% of the energy used in a hot water cure. Previous attempts to extend the use of steam curing of ClPP liners to diameters of 18" and above have often resulted in incomplete curing of the lower portion of the installed ClPP liner. Attempts to solve this curing problem by using larger amounts of water and/or steam and air, have only been partially successful. In addition, the introduction of larger amounts of steam could lead to a longer curing cycle time and increased energy use. Even with a longer curing cycle and more energy, it is difficult to achieve a effective curing under some field conditions. It is believed that this may be due to thermal stratification and the presence of areas of condensation that collect in the lower parts of the pipe and the cured liner. The collected condensate insulates and prevents heat transfer to the resin laminate from the vapor blanket above.

Hot water curing of medium to large ClPP liners typically requires between approximately 1500 to 2500 BTUs per pound of resin being cured. On the other hand, smaller steam cured liners (6" - 12") require about 700 to 100 BTUs per pound of resin being cured.

The described methods achieve sustained ClPP curing between approximately 300 to 500 BTU per pound of resin, even in areas of accumulated condensate at the bottom of the CIPP liner. This is possible due to the use of a steam injection method that regulates the steam injection locations to eliminate thermal stratification and negative effect on the hardening of collected condensate. The process also regulates the amount and location of steam injection along the ClPP liner to maximize the heat transfer from each pound of steam to the resin felt laminate before it is discharged from the far end of the ClPP liner as condensate or steam.

As described here, steam is injected into a closed tube located in the inversion of the expanded ClPP liner. One or more independent discharge ports with a control valve are provided to regulate the discharge of water vapor and condensate from the distal end of the ClPP liner. The hose contains a number of openings of suitable size and spacing, thickness and length of the installation along the entire length of the hose. The location of the opening around the stroke periphery is designed so that a number of openings along the length of the hose, regardless of the direction of the length under the location in the ClPP liner, will be directed towards the bottom of the ClPP liner. This produces a continuous injection of steam into any collected condensate throughout the curing cycle. The steam injected into the condensate heats the condensate above the temperature necessary to ensure curing.

The closed end of the steam injection hose causes the internal pressure in the injection hose to be higher than the internal curing pressure in the ClPP liner. As the injected steam moves through the length of the tubing, it is forced out through openings and forms a steam blanket in the ClPP liner. The difference between the internal pressure in the steam injection hose and the ClPP pressure decreases as the steam moves away from the injection end of the steam injection hose. Consequently, the amount of steam injected from each orifice decreases along the steam injection tube.

This leads to three things:

1. Increase in residence time where most of the steam becomes available in the ClPP liner to maximize energy transfer to the resin felt laminate. 2. Add continuous energy to the vapor blanket as it moves towards the outlet end of the ClPP liner and keep the energy transfer rate higher. 3. Steam injection into the steam blanket also caused turbulence which eliminates thermal stratification and increases energy transfer.

Knowing the physical characteristics of the ClPP liner (diameter, length, thickness, resin and catalyst system) and available boiler capacity in BUT per hour allows the orifice size to be adjusted to match the boiler capacity in pounds of steam per hour with the recommended curing cycle time.

It will be seen that the method according to the invention makes it possible to take advantage of the curing of a resin lining with current through steam. By practicing the method, a pipe element can easily be inverted through an existing pipeline. By providing an apparatus with two rigid gaskets, it is possible to install an inversion liner with a restraint strap and a horizontal, flat hose. The use of gap adjustment devices to maintain the gap at the second packing allows the inverting pressure to be increased to complete the profile of the liner without increasing the packing pressure against the inverting liner. Steam is then introduced into the inverted liner to utilize the higher energy contained in the steam which significantly shortens the curing cycle compared to hot water curing.

Claims (26)

1. Method for inverting a resin-impregnated cured liner (101) in situ in an existing conduit with an installation apparatus (11) having an opening (13) and a first gasket (16) and a second gasket (21) downstream and spaced from the first gasket and downstream of the opening, characterized by: attaching the forward end of the liner (101) to the apparatus opening (13) upstream of the first gasket (16), inverting the liner through the apparatus past at least one gasket, installing a fluid inlet port (108) in the inverted part of the liner (102a, 102b) downstream of at least one gasket, install a second fluid inlet port (106) in the inverted liner located downstream of the second gasket (21) with the first inlet port (108) located between the apparatus's two gaskets (16, 21), close one of the packings (16, 21) with the fluid inlet port on the downstream side thereof, introduce a pressure inversion fluid into the inverted portion of the liner through the fluid inlet port, and allow the liner to invert in response to the fluid entering is introduced through the fluid inlet. 2. Method according to claim 1, characterized in that the inlet port (108, 106) is installed before the liner is attached to the device. 3. Method according to claim 1, characterized by the fact that part of the liner (102a, 102b) placed in the device is inverted before it is attached to and placed in the device. 4. Method according to claim 1, further characterized by: closing the second seal (21) to grip and seal the inverted part of the liner (102a, 102b), introducing curing fluid into the second port (108) in the liner to cure the resin, and cooling the cured guidance. 5. Method according to claim 4, characterized in that it comprises: attaching a retaining strap (111) to the end of the inverting liner and, when the start of the retaining strap is located between the gaskets (16, 21), closing the first gasket (16) and opening the second gasket (21) ) so that the strap (111) can be passed through, and upon completion of the inversion, introduce curing fluid into one of the inlet ports (106, 108). 6. Method according to claim 5, further characterized by attaching a lying flat tube (112) to the distal end of the liner with the restraint strap (111). 7. Method according to claim 6, characterized in that the lying, flat hose (112) is closed at the distal end attached to the liner. 8. Method according to claim 6, further characterized by attaching the horizontal flat hose to the first inlet port (108), closing the first gasket (16) and opening the second gasket (21) and continuing the inversion until the horizontal flat hose (112) rests on the bottom of the lining. 9. Method according to claim 8, characterized in that attaching the horizontal flat hose to the inlet port comprises the steps: cutting the horizontal flat hose (112) upstream of the first gasket (16), attaching one end of a knee (113) to the cut end of the horizontal, flat hose (12), and attach the other end of the elbow (113) to the first inlet port (108). 10. Method according to claim 8, characterized in that attaching the lying flat tube to the inlet port comprises the steps of: cutting the lying flat tube (112) upstream of the first gasket, feeding the cut end of the lying flat tube (112) through the first inlet port (108), insert a flexible, tubular, rigid sleeve with an extended end into the cut end of the horizontal flat tubing, bend the horizontal flat tubing (112) to the tube portion of the sleeve, and insert the horizontal, flat hose (112) and the pipe part of the sleeve in the inlet port (108), where the end of the horizontal flat hose (112) is caught between the extended part of the sleeve and the inlet port (108) and the horizontal flat hose (112) is obstructed in breaking when the sleeve forms a gradual bend towards the second gasket (21). 11. Method according to claim 6, characterized in that the lying, flat hose (112) is perforated along its length to distribute hardening fluid along the interior of the inverted liner. 12. Method according to claim 6, characterized by the steps of closing the first seal (16) after the horizontal, flat hose (112) and restraint band (111) connection is passed through it and opening the second seal (21) so that the connection can pass and continue to invert the liner. 13. Method according to claim 1, characterized by the step of porting the downstream end of the inverted liner after the inversion is completed without emptying the inverted liner. 14. Method according to claim 4, characterized in that the inversion fluid is air and that the curing fluid is steam. 15. Air inversion and steam curing apparatus (11) for installing a resin-impregnated cured pipe liner (101) on site, having a rigid frame (12) with an opening (13) for passing the liner (101) therethrough and first and second gaskets mounted on the frame downstream of the opening, characterized by means (17) for securing an inverted part of the lining at the opening, each packing (16, 21) has at least one selectively movable rigid packing member (18, 23) for adjusting the gap of the packing to engage the inverted liner passed therethrough. 16. Apparatus according to claim 15, further characterized by motors (19, 24) connected to the movable elements to adjust the space between the packing elements. 17. Apparatus according to claim 15, characterized in that at least one motor (19, 24) is mounted on the frame (12) and connected to the movable packing elements (18, 23). 18. Apparatus according to claim 16, characterized in that it further comprises a motor (19, 24) mounted on the frame (12) at the end of each movable packing element (16, 21). 19. Apparatus according to claim 16, characterized in that the motors (19, 24) are pneumatic cylinders mounted on the rigid frame (12). 20. Apparatus according to claim 15, characterized in that the movable packing elements (18, 23) are moved on linear guide bearings mounted to the frame. 21. Apparatus according to claim 15, characterized in that the space between the packing elements (18, 23) of the second packing (21) is fixed at a minimum by means of a space adjustment device to limit the movement of the movable elements (18, 23). 22. Apparatus according to claim 21, characterized in that the space adjustment device is at least a spacer of a desired size for placement on the guide bearings (21a) between the packing elements (22, 23). 23. Apparatus according to claim 21, characterized in that the space adjustment device is an adjustment bolt which can be adjusted to limit the movement of the movable packing element (23). 24. Apparatus according to claim 15, further characterized by several hooks (14) arranged on the frame (12) upstream of the first gasket for mounting the liner (101) to be inverted. 25. Apparatus according to claim 15, characterized in that the packing elements (17, 18, 22, 23) are rigid metal rods. 26. Apparatus according to claim 15, characterized in that the packing elements (17, 18, 22, 23) are metal tubes.